Regenerative radioreceiver



1933- w. VAN B. ROBERTS REGENERATIVE RADIORECEIVER Filed Nov. 22, 1930 INVENTOR WALTER VAN B. ROBERTS ATTORNEY Patented Oct. 17, 1933 i s I i i it s UNITED TA OFFICE If REGENERATIVE RADIORECEIVER Walter Van B. Roberts, Princeton, N. J assignor,

to Radio Corporation ot America, acorporavtion of Delaware Application November '22, 1930- Serial No. 497,368

3 Claims; (o1. 250-20) My present inventionrelates to radio receivregeneration and amplification inthe receiver;

ers, and more particularly to a portable, or r'noa result not possible in the prior art," bile, radio receiver utilizing a novelmethod of -Accordingly, it is one ofthe main objects 01' l cascade regeneration. c my present invention td'provide a radio'receiver,

5 In additionto being economical in its conespeciallyadaptedlfor portable use, wherein there sumption of power, a, portable radio receiver is employed a screengrid'amplifiertube feeding should possess as great a degree of selectivity and a radio frequency system containing .regenera sensitivity as is possible without impairing too tive arrangements, the screen grid tube being fed greatly its fidelity. To secure these characterlsby a resonant collecting circuit also containing tics, it has been customary in the prior art to a regenerative arrangement, the. first mentioned employ regenerative circuits in portable receiv radio frequency system being shielded from the ers. However, the use ofregenerative circuits is second radio frequency system, and the regeneraattendant with various disadvantages tending to tion of the collecting circuit being obtained by discourage the/wide use of portable receiver's. the meet a tube which is provided for that One of the important disadvantages depends purpose exclusively. 70

upon the fact that asingle regenerative stage Another important object of the invention is" i I does not give sufficient amplification without to provide in a radio'receiver an arrangement: critical tuning and regenerative adjustment, whereby two successive tuned circuits are conand without great loss of fidelity. pled by a space discharge device including a In such cases, oneor more, non-regenerative screen grid electrode, means for regenerating the stages connected in cascadeahead of the resucceeding tuned circuit, and an auxiliary space, generative stage are usually employed. If, howdischarge device for regenerating the preceding, ever, a plurality of regenerative stages is emtuned circuit. f ployed in cascade, the selectivity curve, is least Another object of the invention is to providea sharp (fidelity best) when sufilcient regeneraportable receiver containing atunable loop tion is used in the various tuned circuits to tenna connected acrossthex input electrodes of make their apparent tuning factors or coil efii-M a. scr'een'grid tube,,an electron discharge tube, ciencies about equal, rather than to get the decircuit for regener'ating the' input, circuit of the sired amplification all in one regeneration. That screen grid tube, and a succeeding screen grid.

it to say, it, has been found that better results tubedetector havingits input circuit tuned and are secured, from the point of view of selectivity regenerated; 1 q H and fidelity, when a plurality of tuned radio Still other objects of the inventio'n are to im-' stages are connected in cascade, eachincluding prove generally thesimplicityand efficiency of means forjregenerating its tuned input circuit, portable radio receivers, andto particularlyp q than to employ regeneration only in one of the vide'a portable receiver which is not only durable.

cascadedtuned radio stages. and reliable in operation, but economically manu-i Now, I have found-that two non-critical refactured and operated. "f; I i c generations give more sensitivity and are easier 1 The novel featuresflwhich I'believe to be chair. to adjust than a single critical regeneration, proacteristic of my invention are set forthjinpar- 4'0 vided a tube with good, screening is utilized beticularity in thefappended claims, the invention, tween cascaded tuned circuits, so that the tunedv itself, however, asj-tobothfits organizationand circuits are thoroughly shielded from each methodof operation will best be understood" by other; Thus, the total regenerative eifect is reference .to the [following description takenin truly cascaded; that is to say, the product of connection with thedrawing in which I have the two separate effects. Further, Ihave disindicated,diagranimatically one circuit organiza-f' covered that portable receivers can be made much tion whereby my inventionrni'ay be, carrieduinto more eflicient than those constructed in the prior efiect. H s s art by utilizing in addition to the aforementioned For further details .of the invention, referenc arrangement, a means for separately regeneratis made to the drawing, in which .the single figure,

50, ing the tuned input circuit of the first of the shows, one embo'diment of the invention; which 9 stagesof alplurality oftuned radio stages configure diagrannnatically shows, a radio receiver nected in cascade, the succeeding stage employcircuit, especially adapted for portability, and. ing" the usual reactive coupling between output which circuit comprises generally a loop antenna and input circuits for regeneration. In this way, 1 having a variable tuning condens'erconnected it ispossible toprocure independency between the across fits outputterminals, While the 10 m llQ i cathode 6 of the tube.

lecting means has been conventionally shown, it

is to be clearly understood that its construction may follow any arrangement well known to those skilled in the prior art, and may be arranged on the receiver in such a manner that it can be readily disposed of when the receiver is being carriedfrom one location to; another. The circuit in addition, preferably comprises a pair of successive tuned circuits, both including space discharge devices 3 and 4. I l

The circuit including the device, or tube; 3

1 and a space charge electrode 9 disposed between the cathode 6 and the controlelectrode 5. As

shown, the tube 3 requires relatively little operating voltage, the space charge electrode 9 necessitating but six volts, the screen electrode having twenty-two volts impressed upon. it, while the anode '7 has but 45 volts impressed upon it. 1

The tube 3 is preferably a pentode tube in order to economize the battery voltage, it being pointed out, however, that a screen grid tube without the space charge electrode 9 'may also be utilized. It is desirable, however, that whatever type of tube be employed in place ofthe pentode tube 3, such a tube require little voltage, in order to minimize the weight of batteries usually provided in a portable radio receiver. v

The amplified output of tube 3 is impressed upon the input circuit of the "succeeding device,

or tube, 4 by means of a transformer coupling M, the primary coil 10 oi the latter being connected in series with the anode 7, the secondary coil'11 being connected in series between the control electrode and the cathode of tube 4.. A variable tuning condenser2 is connected across the coil 11 and between the cathode and control electrode of .tube 4, the usual series capacity and shunt grid leak resistance being connected in the control electrode circuit of thetube in order to permit tube '4 to function as a detector. The anode circuit of tube 4 is reactively coupled to its input circuit through a coil 12, the latter being connected in series in the anode lead 13, means being providedto vary the feed-back fromthe output to the input circuit by providing a variable coupling between coils 12 and 13, such means being conventionally designated by the arrow 14.

" l, 1 The detector tube 4 preferably employs a screen grid electrode, thus permitting regeneration control as free as possible from any sudden fsnapping into oscillation. Aradio frequency choke coil 15 is provided in series in' the anode lead 13 in order to by-pass radio frequency currents through'the-radio frequency condenser 16 connected between the anode and the cathode of tube 4. The output circuit of detector tube 4 may be connected to any desired utilization means, the

- I latter comprising one or more stages of audio frequency amplification, and/or head-phoneb, loud speaker and the like. 1

The tuned input circuit, which consists of the loop antenna 1 and the tuning condenser 2, of

the pentode tube 3 is regenerated by means of an auxiliary space discharge device, or tube, 16.

The control electrode of. the latter is connected to the lead 1'7 between one side of the tuning condenser 2 and the control electrode 5. The cathode of tube 16 is connected between the other termi-;

119.1 of condenser 2 and the cathode 6 of the tube feed-back arrangements.

3. The tube 16 is rendered regenerative by means of the conventional tuned'anode'cir'cuit arrangement comprising a variometer' 18 connected in series in the anode circuit. The feed-back, as is well known, is secured through the inherent capacity between the grid and anode of tube 16, such inherent'capacity 19 being shown in dotted lines.

A radio frequency by-pass capacity 20 is connected between thecathode and anode circuit of tube 16, while the latter is connected to a source of voltage (not shown) adapted to supply somewhat less than twenty-two volts to the anode. ;It will be appreciated that the tubev 16 I may be or" a type thatconsumes very little power,

and therefore highly economical for use in a portable radio receiver. Proper adjustment of the variometer 18 results in the desired amount of regeneration. of the tuned input circuit of pentode tube 3. The tube 16, if, desired, may

include a screen grid electrode, with suitable A shielding means 21 "shown in dotted line,

is provided aroundthe tubes 3 and 4. The shield- 7 ing. does not include the choke coil 15, the cir-v cuits of tubes 16 or the tuned loop circuit 1, 2;

the shielding means being grounded, as at G. If

desired, the tuning condensers 2 and 2 can be arranged for mechanical uni-control, the latterv being represented diagrammatically by the dotted lines-22. The purpose of the shielding arrangement 21 is to preventthe reaction of the regenerative'circuit of the tube 4 upon the tunable loop circuit 1, 2. v

The operation of the receiver described heretofore in detail; should be obvious from such, do

tailed description, it'being necessary only to point out that by separately regenerating the input circuit of tube 3, there is securedfan independency of regeneration and amplification of'tub'e crating the input circuit of tube 3 from'f'a separate tube, independency of regeneration and amplification is secured. I N v It will, also, be seen that byproviding a, screen grid in tube 3, which thoroughly shields the tuned circuit 1, 2 from the tuned circuit 11,52 the total regenerative effect of the circuit is truly cascaded.

That is to say, there is obtained in the output circuit of the detector tube 4 the product of the two separate regenerative effects, thereby #y'ield- It can be shown that ing more sensitivity and easier adjustments than would be the case with a single, critical regeneration, it, beingunderstood of course th'at the Y regenerations employed in each of the stages are non-critical.

If the circuits are not well shielded, the coupling will act regeneratively on the first circuit, the

phase and amount of this feed-back depending'on" the relative'tuning of the two circuits." The tunings required for best amplification may be,,such

as to produce too much ortoo little regeneration,

and since both the regenerative amplification and the normal tube" amplification are affected at once it is difiicult, or impossible to adjust both to desired values simultaneously. It is to allow this complete shielding that the auxiliary regenerating tube must be used.

To manipulate the present receiver, it is merely necessary to set the tuning means 22 to the desired 150. I

signal reading, and then adjust the control 18 and 1 until the desired amplification is secured, more exact tuning being attained by means of Vernier capacities a and a1 operable independently. It 'will be found that high amplification, good selectivity and fidelity characteristics are secured by means of the present arrangement,

one circuit, its apparent resistance will be reduced to 0.2 ohms which is so low as to seriously impair fidelity.

, While I have indicated and described one arrangement for carrying my invention into effect,

it will be apparent to one skilled in the art that my invention is by no means limited to the par ticular organization shown and described, but

that many modifications may be made without departing from the scope of my invention as" set forth in the appended claims.

What I claim is: i

1. A radio receiver comprising a tunable loop circuit adapted to intercept transmitted signal energy, a screened grid tubeiprovided with an output circuit and a tuned input circuit connected to the loop circuit, an electron discharge tube provided with an output circuit regenera-' tively coupled to its input circuit, said electron discharge tube being connected so as to act as a regenerative detector, means for tuning said last named input circuit, the output circuit of the screened grid tube being coupled to the input circuit of the second tube, an independent electron discharge device having its input circuit shunted directly across the input of the screened grid tube, said independent device having a tunable output circuit for regenerating the tuned input circuit of the screened grid tube whereby there is obtained in the output circuit of the second tube substantially the product of the two separate regenerative efiects, a utilizing means connecting circuit coupled to the output of the electron discharge tube including filter means comprising a path of low impedance for high frequency energy and a path of high impedancefor high frequency energy and a shielding means for shieldingly enclosing only said screened grid tube, said regenerative detector including the coupling means between the output of the screened grid tube and the input of the regenerative detector and the path of low impedance for high frequency energy.

'2. In a radio receiver, a stage of radio frequency amplification comprising a screened grid tube having input and output circuits, a loop ergy connected across said input circuit and said input circuitfor tuning said loop and input circuit to the frequency of desired signal energy, an electron discharge device having an input so circuit for intercepting transmitted signal en- 1 means comprising a variable tuning devicei n circuit andan output circuit, said input circuit thereof being linked with said output circuit of said electron discharge device to facilitate the transfer of energy from said output circuit to saidinput circuit thereof for producing regeneration, means associated withsaid electron disa charge device for giving thereto a detector tube characteristic whereby said-electron discharge device acts as a regenerative detector, means circuitof said electron discharge device for tuning the input circuit thereof, an additional electron discharge device having an input circuit and an output circuit, said inputcircuit being shunt ed directly across the input-circuit of r the screened grid tube, the input circuit of said additional electron discharge device being linked with the outputcircuitthereof to facilitate the transfer of energy from said output circuit to the input circuit thereof for producing regeneration in thetuned input circuit of the'screened comprising a variabletuning devicein the input grid tube, said screened grid tube acting to shield the tuned input circuit thereof from the tuned input circuit of the first mentioned electron discharge device whereby there is obtained in the output circuit of the first mentionedielectron discharge device substantially the product of the 'two separate regenerative effects, a utilization coupling means connected in the'output circuit of the electron discharge tube including filter" means comprising a path of low impedance for high frequency energy and a path of highim-' pedance for high frequency energy.

3. The system described in the next preceding claim in combination Witha shielding meansfor enclosing only said screened grid tube, said regenerative detector including the coupling means between the output of the screened grid p tube and the input of the regenerative detector and the path of low impedance for high fre quency energy whereby stray energy emanating from thecircuits of said regenerative detector is, in effect, localized within said shielding means and thereby substantially prevented from affecting the input circuit of the screened grid tube. V

WALTER VAN B. ROBERT 

